if you're running the server locally then you should be connecting your local client as follows:

For PC’s connecting on the same LAN as the server:If you’re connecting the client from a different PC than the server then configure the client to use one of the internal ipaddresses of the server for the servername.

If you’re running the client on the same PC as the server then configure the client to use 127.0.0.1 or “localhost” as the Hostname (ipaddress).

Most home routers will not loopback a connection if you specify your external ipaddress or DNS hostname in the Ventrilo Client > Server setup. In most cases this configuration has caused unexpected problems.

the problems arises if you use your external ipaddress or DNS hostname in the client setup. i have seen many problems show up as a result of this configuration, including the one that you're having, which is why i want to make sure your client is set correctly.

did you setup any inactivity timers in the server properties? rt-clik in window/server admin/server properties